Acquisition of Laser Ablation System to Quantify Matrix and Grain-boundary Trace Element Partitioning in Olivine and Pyroxenes: an Integrated Bulk and In Situ Approach

获取激光烧蚀系统来量化橄榄石和辉石中的基体和晶界微量元素分配：一种集成的散装和原位方法

• 批准号: 0549268
• 负责人: Cin-Ty Lee
• 金额: $ 11.51万
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-15 至 2007-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0549268&HistoricalAwards=false
• 关键词: Acquisition; Laser; Ablation; System; Quantify

0549268LeeIntellectual merit: Trace element signatures of magmas and the solid residues of melting can be powerful tools for deciphering the physical processes of melting and magma segregation on Earth. However, these tools can only be used if the partitioning of such trace elements between minerals and melt is well understood. The goal is to investigate trace element partitioning of major mineral phases in the mantle, where most melting takes place. Emphasis will be on olivine and orthopyroxene, which are the dominant minerals in the upper mantle, but the least understood in terms of partitioning. This poorer understanding of partitioning compared to that of clinopyroxene is due to contamination effects from melts and analytical difficulties (trace element concentrations in olivine and orthopyroxene are often very low). To avoid melt contamination effects, a semi-theoretical model for trace element partitioning between olivine, orthopyroxene and clinopyroxene matrices at subsolidus conditions is developed and calibrated using mantle xenoliths. These subsolidus matrix partition coefficients will then be corrected-up for temperature and related to known clinopyroxene/melt partition coefficients, yielding a consistent set of mineral matrix/melt partition coefficients for upper mantle phases. This will be followed by testing of a recent hypothesis that mineral grain boundaries (e.g., rims) are significant repositories for trace elements due to equilibrium partitioning between grain interiors (matrix) and boundaries. Grain boundary partitioning will be assessed by quantifying the deviation from matrix partitioning theory above. Both steps will be facilitated by the addition of laser ablation capabilities to existing mass spectrometry facilities at Rice (ICP-MS) by enabling the measurement of matrix partition coefficients and the screening of disequilibrium samples.Broader Impacts: Components of this study will be parsed out for undergraduate research. Acquisition of a laser will also benefit other ongoing studies as well as help to entice more undergraduates into doing research by expanding the breadth of research projects at Rice and other institutions in the Houston area.

0549268Lee智力价值：岩浆的微量元素特征和熔化的固体残留物可以成为破译地球上熔化和岩浆分离的物理过程的有力工具。 然而，只有充分了解这些微量元素在矿物质和熔体之间的分配，才能使用这些工具。 目标是研究地幔中主要矿物相的微量元素分配，大部分熔化发生在地幔中。 重点将放在橄榄石和斜方辉石上，它们是上地幔中的主要矿物，但在分配方面却知之甚少。 与单斜辉石相比，对分配的了解较差，这是由于熔体的污染影响和分析困难（橄榄石和斜方辉石中的痕量元素浓度通常非常低）。 为了避免熔体污染效应，开发了亚固相线条件下橄榄石、斜方辉石和单斜辉石基质之间微量元素分配的半理论模型，并使用地幔捕虏体进行了校准。 然后，这些亚固相线基质分配系数将根据温度进行校正，并与已知的单斜辉石/熔体分配系数相关，从而产生上地幔相的一组一致的矿物基质/熔体分配系数。随后将测试最近的假设，即由于晶粒内部（基体）和边界之间的平衡分配，矿物晶界（例如边缘）是微量元素的重要储存库。 将通过量化与上述矩阵分配理论的偏差来评估晶界分配。 通过在莱斯大学现有的质谱仪 (ICP-MS) 中增加激光烧蚀功能，可以测量基质分配系数并筛选不平衡样品，这两个步骤将得到促进。 更广泛的影响：本研究的组成部分将被解析出来供本科生研究使用。 购买激光器还将有利于其他正在进行的研究，并通过扩大莱斯大学和休斯顿地区其他机构的研究项目的广度，帮助吸引更多本科生进行研究。